7: Derivatives
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”There is nothing permanent except change.” - Heraclitus
Chapter seven is where limits deliver their biggest performance yet: the derivative. We will see how a specific limit can tell us the slope of the line tangent to a curve at a given point. In loose terms, it is the slope of the curve at one point. While this does not sound overly impressive on its own, consider that we will see the word derivative in every future chapter of this book!
We start by learning the formula for finding the derivative of a function at a point, and get plenty of practice taking a special limit. When this limit gets too hard, we offer a different (but equivalent) limit option. While these limits are sometimes of the more difficult variety, we explore a few different challenges and how to overcome them by using either of the two different aforementioned limit methods.
We finish the chapter with a more formal discussion on what a derivative is, and when it should or should not exist for a given function. We also discuss how a derivative will effect/be effected by the graph of a function.
This is the chapter where a student should be able to put their algebra skills learned thus far to the test to help solve a problem by using limits. Being able to evaluate a derivative or find a tangent line in this way is critical to understanding why we are allowed the shortcuts and patterns we will use in the future to take derivatives.